1. Field of the Invention
The present invention relates to improving efficiency of gasoline engines, and more particularly to supplementary introduction of fuel into the intake manifold at a point other than by co-existing fuel injection valves.
2. Description of the Prior Art
Careful control over the quantity of fuel fed to gasoline engines has been the subject of great attention in the prior art. The purpose of such control includes economy of fuel consumption; compliance with pollution emission limits; power and response of an engine; and increased longevity of an engine, as by reducing carbon deposits therein.
It has been the experience of the automotive industry that some of these purposes, and in particular, the first two mentioned above, frequently work at cross purposes. Precise fuel control, as provided by electronically controlled fuel injection systems seem to offer the best hope for addressing all these concerns satisfactorily. Therefore, refinement to fuel control may be expected to be reflected in fuel injection systems. Patents disclosing incorporation of one significant refinement relevant to the present invention are discussed below.
U.S. Pat. Nos. 3,890,946, issued to Josef Wahl on Jun.24, 1975, and 3,960,118, issued to Toshiaki Konomi et al. on Jun.1, 1976, each show an engine fuel arrangement wherein a carburetor is purposefully designed to provide a lean mixture. A supplementary fuel injection valve is provided to make necessary adjustments to the fuel-to-air ratio. An exhaust sensor monitoring exhaust gases for oxygen content provide the input to a microprocessor or equivalent device, which in turn sends a control signal to the fuel injection valve. The fuel injection valve provides a compensating and complementary quantity of fuel to the engine responsive to the control signal.
Still further examples generally illustrating the approach described above are seen in U.S. Pat. Nos. 4,088,100, issued to Naomi Tokura et al. on May 9, 1978, and 4,169,441, issued to Tadayoshi Hirano et al. on Oct. 2, 1979.
Japanese Pat. Application No. 63-307639, dated Jun. 12, 1990, provides two fuel injection valves to accomplish the same result. One of these injection valves is responsive to a signal derived from an exhaust sensor.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.